1. Field of the Invention
The present invention relates in general to telephone systems, and more particularly to a message-waiting signalling arrangement for use in a PBX telephone system.
2. Description of the Prior Art
The concepts of message waiting have been applied principally to private branch exchange telephone systems. In such systems a central switchboard operator controls the message-waiting indicators using additional switching and access circuitry consisting of manually operated keys and signalling lamps.
When it was required to signal a station that a call is waiting, the attendance was required to dial the station line number and then operate a "call waiting" key at the attendance position. A lamp at the called station would then flash on and off, indicating that a call is waiting for this particular station.
The additional circuitry included an access relay for each subscriber station arranged for this feature as well as a signal distribution bus and control arrangements therefor.